[DTrace-devel] [PATCH 3/4] Drop counters support

[Eugene Loh]

On 5/10/23 23:04, Kris Van Hees wrote:

> On Wed, May 10, 2023 at 10:52:12PM -0400, Eugene Loh via DTrace-devel wrote:
>> The R-b is still good, but...
>>
>> On 5/9/23 03:19, Kris Van Hees via DTrace-devel wrote:
>>> diff --git a/test/unittest/drops/drp.DTRACEDROP_PRINCIPAL.d b/test/unittest/drops/drp.DTRACEDROP_PRINCIPAL.d
>>> -#pragma D option bufsize=512
>>> +#pragma D option bufsize=3k
>>> diff --git a/test/unittest/drops/drp.DTRACEDROP_PRINCIPAL.end.d b/test/unittest/drops/drp.DTRACEDROP_PRINCIPAL.end.d
>>> -#pragma D option bufsize=512
>>> +#pragma D option bufsize=3k
>> Saying bufsize=3k does not seem fair when...
> What do you mean with "fair"?

It seems misleading.  It suggests that we're carefully specifying a 
peculiar value to effect a certain test, but what actually happens is 
the test changes what we specified.

Why not just say bufsize=4k in the test?  That'd be clearer and more direct.

> The settings ensure that we can trace a certain
> amount of data, but not all (so that we get a drop).  Yes, the implementation
> is currently needing to enforce a buffer size that is a whole multiple of the
> pagesize, and that will indeed be reported in the test output.  Which means
> that if the required buffer size changes we will get an expected output
> failure which is a good thing - it will explain why the test is not going to
> report a drop.
>
> But the values are chosen to ensure that we both have data reocrded *and* a
> drop.
>
> I deliberately chose the limit below the minimum (but large enough for the
> test).
>
>>> diff --git a/test/unittest/drops/drp.DTRACEDROP_PRINCIPAL.end.r b/test/unittest/drops/drp.DTRACEDROP_PRINCIPAL.end.r
>>> +bufsize increased to 4096
>>> diff --git a/test/unittest/drops/drp.DTRACEDROP_PRINCIPAL.r b/test/unittest/drops/drp.DTRACEDROP_PRINCIPAL.r
>>> +bufsize increased to 4096
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